Separator for multi-phase slug flow and method of designing same

ABSTRACT

A slug flow separator facilitates the separation of a mixture flow into component parts. The separator includes an upper-tier elongate conduit, a lower-tier elongate conduit and a plurality of spaced apart connectors. Each of the upper and lower-tier elongate conduits has an outlet and at least one of the upper and lower-tier elongate conduits has an inlet for receiving the mixture flow. The upper and lower-tier elongate conduits also each have a plurality of openings such that one connector of the plurality of connectors may interconnect one of the upper-tier elongate conduit openings with a one of the lower-tier elongate conduit openings. The connectors enable communication of at least one of a liquid component and the at least one of another liquid component and a gas component of the mixture flow therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Non-Provisionalpatent application Ser. No. 11/284,304 filed Nov. 21, 2005, which hasissued as U.S. Pat. No. 7,540,902, and which claims priority to U.S.Provisional Application 60/630,890 filed on Nov. 24, 2004. U.S.Provisional Application 60/630,890 filed on Nov. 24, 2004 is hereinincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates generally to handling a flowing mixture, and morespecifically to progressive separation of a slug flow into constituentparts within closed pipelines based at least in part on the principlesof buoyancy and gravity.

In the field of oil production and transmission, flows of two-phasemixtures (e.g., gas-liquid mixtures) (hereinafter referred to as“two-phase flows”) or other mixtures of constituent parts having varyingdensities (e.g., liquid-liquid mixtures, gas-liquid mixtures, gas-gasmixtures) (hereinafter referred to as “mixture flows”) are commonlyencountered. This is especially true in production carrier pipelinesconveying oil mixtures from a producing well. Producing wells, forexample, may contain a mixture of oil, water and various gases that areextracted as a mixture flow through a pipeline. These flows must bereceived by oil handling systems and separated into constituent orcomponent parts based on phase or density for treatment and subsequentdistribution to end users.

It is often desirable for flow separation of a mixture to occur prior tothe transmission thereof through significant lengths of pipelines. Earlymixture flow separation enables mechanical devices functioning withinoil production and transmission systems to manage component flows eachhaving substantially only one phase or range of densities. Examples ofsuch mechanical devices include compressors utilized for compressingmaterials in gaseous states and pumps for moving the flow of liquids. Bymanaging component flow of a single phase or density range, thesemechanical devices can be engineered for optimum performance whilereducing stresses placed on respective oil handling systems.

Mixture flow separation, however, is not without its difficulties. Firstof all, many producing wells are positioned at remote locations and inharsh environments, such as on a deep sea floor. In those situations,achieving separate component part flows shortly after the correspondingmixture flow (which may, for instance, include a two-phase flow) leavesthe well requires a separation system to be located where it is not easyto install nor easy to access when system maintenance is needed.Further, most conventional systems that achieve efficient componentseparation may be quite bulky and heavy, reducing the desirability ofusing such separation systems on overseas platforms where weight andspace considerations are a high priority.

One separation system design involves the use of a centrifugal forceseparator: essentially a curved pathway in a transmission or carrierline with one or more radial ports or annular channels. When a mixtureflow achieves a sufficient velocity, centrifugal force will move thedenser component (e.g., liquid) to the outside of the curve and into theports or channels that carry the liquid into a storage container. Whilethis design achieves a certain degree of separation for some mixtureflows, it is not very effective for mixtures in the form of slug flows.Slug flow refers to an uneven distribution of components in a mixtureflow that creates undesirable cyclic flow characteristics for themixture. Due to slug flow, surges of components of the flowing mixture(e.g., gas or liquid) may be realized at any given point along thetransmission pipeline, impeding efficient mixture flow and causingincrease stresses on mechanical devices of the transmission system.Because the mixture flow components often do not arrive at variouspoints in transmission at the same time, centrifugal force separatorshave a difficult time properly segregating the mixture flow componentsfrom one another. Thus, the prior art has not provided a solution forseparating mixture flows into constituent parts in a simple andeffective manner.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a separator is provided forsubstantially separating a two-phase flow into a gas component and aliquid component. The separator includes an upper-tier elongate conduit,a lower-tier elongate conduit and a plurality of spaced apartconnectors. Each of the upper and lower-tier elongate conduits has anoutlet and at least one of the upper and lower-tier elongate conduitshas an inlet for receiving the two-phase flow. The inlet is positionedopposite the outlet relative to at least one of the plurality ofconnectors. The upper and lower-tier elongate conduits also each have aplurality of openings such that one connector of the plurality ofconnectors may interconnect one of the upper-tier elongate conduitopenings with one of the lower-tier elongate conduit openings. Theconnectors enable communication of at least one of the gas component andliquid component therebetween.

In another aspect, the invention provides a separator for substantiallyseparating a mixture flow into a liquid component and at least one ofanother liquid component and a gas component. The separator includes anupper-tier elongate conduit, a lower-tier elongate conduit and aplurality of spaced apart connectors, the upper and lower-tier elongateconduits being parallel with one another. Each of the upper andlower-tier elongate conduits has an outlet and at least one of the upperand lower-tier elongate conduits has an inlet for receiving the mixtureflow. The upper and lower-tier elongate conduits also each have aplurality of openings such that one connector of the plurality ofconnectors may interconnect one of the upper-tier elongate conduitopenings with a one of the lower-tier elongate conduit openings. Theconnectors enable communication of at least one of the liquid componentand the at least one of the another liquid component and a gas componenttherebetween.

In another aspect, the invention provides provides a separator forsubstantially separating a mixture flow into a liquid component and atleast one of another liquid component and a gas component. The separatorincludes an upper-tier elongate conduit, a lower-tier elongate conduitand a plurality of spaced apart connectors, the upper-tier elongateconduit being spaced from and above the lower-tier elongate conduit.Each of the upper and lower-tier elongate conduits has an outlet and atleast one of the upper and lower-tier elongate conduits has an inlet forreceiving the mixture flow. The upper and lower-tier elongate conduitsalso each have a plurality of openings such that one connector of theplurality of connectors may interconnect one of the upper-tier elongateconduit openings with a one of the lower-tier elongate conduit openings.The connectors enable communication of at least one of the liquidcomponent and the at least one of the another liquid component and a gascomponent therebetween.

In another aspect, the invention provides a separator for substantiallyseparating a mixture flow into a liquid component and at least one ofanother liquid component and a gas component. The separator includes anupper-tier elongate conduit, a lower-tier elongate conduit and aplurality of spaced apart connectors, wherein the connectors are alignedgenerally perpendicular to a horizontal reference plane. Each of theupper and lower-tier elongate conduits has an outlet and at least one ofthe upper and lower-tier elongate conduits has an inlet for receivingthe mixture flow. The upper and lower-tier elongate conduits also eachhave a plurality of openings such that one connector of the plurality ofconnectors may interconnect one of the upper-tier elongate conduitopenings with a one of the lower-tier elongate conduit openings. Theconnectors enable communication of at least one of the liquid componentand the at least one of the another liquid component and a gas componenttherebetween.

In another aspect, the invention provides a separator for substantiallyseparating a mixture flow into component parts based on the densities ofthe component parts. An upper-tier elongate conduit, a lower-tierelongate conduit and a plurality of spaced apart connectors form theseparator. Each of the upper and lower-tier elongate conduits has anoutlet and at least one of the upper and lower-tier elongate conduitshas an inlet for receiving the mixture flow. The inlet is positionedopposite the outlet relative to at least one of the plurality ofconnectors. The upper and lower-tier elongate conduits also each have aplurality of openings such that one connector of the plurality ofconnectors may interconnect one of the upper-tier elongate conduitopenings with a one of the lower-tier elongate conduit openings. Theconnectors enable communication of at least one of the component partstherebetween.

In another aspect, the invention provides a separator for substantiallyseparating a mixture flow into a liquid component and at least one ofanother liquid component and a gas component. An upper-tier elongateconduit, a lower-tier elongate conduit and a plurality of spaced apartconnectors form the separator. The lower-tier elongate conduit is spacedfrom and below the upper-tier elongate conduit such that the lower-tierelongate is parallel with the upper-tier elongate conduit. Each of theupper and lower-tier elongate conduits has an outlet and at least one ofthe upper and lower-tier elongate conduits has an inlet for receivingthe mixture flow. The inlet is positioned opposite the outlet relativeto at least one of the plurality of connectors. The upper and lower-tierelongate conduits also each have a plurality of openings such that oneconnector of the plurality of connectors may interconnect one of theupper-tier elongate conduit openings with a one of the lower-tierelongate conduit openings. The connectors are aligned generallyperpendicular to a horizontal reference plane, and enable communicationof at least one of the liquid component and the at least one of theanother liquid component and a gas component therebetween.

In another aspect, the invention provides a system for substantiallyseparating a mixture flow into component parts. The system includes anarray of upper-tier elongate conduits laterally spaced apart from oneanother, an array of lower-tier elongate conduits laterally spaced apartfrom one another, and a plurality of connectors. Each conduit of thearray of upper and lower-tier elongate conduits has an upstream end, adownstream end with an outlet, and a plurality of openings spaced apartalong the length of the conduit between the upstream and downstreamends. At least one of the array of upper-tier elongate conduits and thearray of lower-tier elongate conduits includes inlets at the upstreamends thereof for receiving the mixture flow. Each connector isconfigured for interconnecting a corresponding one of the plurality ofopenings of one of the upper-tier elongate conduits with a correspondingone of the plurality of openings of the lower-tier elongate conduits toenable communication of at least one of the component partstherebetween.

In another aspect, the invention provides a method of slug flowseparation. The method involves introducing a slug flow comprising aliquid component and at least one of another liquid component and a gascomponent into a separator at a predetermined velocity. The separatorincludes an upper-tier elongate conduit and a lower-tier elongateconduit connected to the upper-tier elongate conduit, at least one ofthe upper-tier and lower-tier elongate conduits having an inlet and eachof the upper-tier and lower-tier elongate conduits having an outlet. Ata next step, substantially separation of the liquid component from theat least one of the another liquid component and the gas component takesplace within the separator. The liquid component is then substantiallyexpelled out through the outlet of one of the upper-tier elongateconduit and the lower-tier elongate conduit. Finally, the at least oneof the another liquid component and the gas component is substantiallyexpelled out through the outlet of another one of the upper-tierelongate conduit and the lower-tier elongate conduit.

In another aspect, the invention provides a method for designing aseparator for substantially separating a slug flow given a maximumhydrodynamic slug volume to be handled by the separator. The slug flowhandled by the separator comprises a liquid component and at least oneof another liquid component and a gas component. In a first step of themethod, an upper-tier elongate conduit is selected having apredetermined inside diameter and length. The upper-tier elongateconduit includes a plurality of openings spaced apart along the lengththereof and an outlet. Next, a lower-tier elongate conduit is selectedhaving a predetermined inside diameter and length. The lower-tierelongate conduit likewise includes a plurality of openings spaced apartalong the length thereof and an outlet. A plurality of connectors arethen selected. Each connector interconnects a corresponding one of theplurality of openings of the upper-tier elongate conduit with acorresponding one of the plurality of openings of the lower-tierelongate conduit, thereby enabling enable communication of the liquidcomponent and the at least one of the another liquid component and thegas component therebetween. Each of the connectors has a predeterminedinside diameter and length. The total number of connectors selected isbased on the predetermined inside diameter and length for the upper-tierelongate conduit, the lower-tier elongate conduit, and each connectorsuch that the total interior volume of the separator is at least aboutthe maximum hydrodynamic slug volume.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a separator in accordance with oneembodiment of the present invention;

FIG. 2 is a side elevational view of the separator of FIG. 1, showing arepresentative flow pattern for a mixture flow within the separator;

FIG. 3 is a side elevational view of the separator of FIG. 1 tilted witha downward slope;

FIG. 4 is a side elevational view of another embodiment of a separatorof the present invention having only an inlet in a lower-tier elongateconduit;

FIG. 5 is a side elevational view of another embodiment of a separatorof the present invention having a third tier elongate conduit; and

FIG. 6 is a perspective view of an embodiment of a separation system ofthe present invention implementing arrays of upper and lower-tierelongate conduits.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures, wherein like reference numbers indicatelike components, and in particular to FIG. 1, a separator of oneembodiment of the present invention is indicated generally by thenumeral 100. The separator 100 is configured to substantially separate amixture flow (including two-phase flows) into component parts based onthe corresponding density of each component part. The mixture flow maybe a gas-gas mixture, a gas-liquid mixture, or a liquid-liquid mixture,as examples. The separator 100 is particularly useful in applicationswhere the mixture flow is a slug flow because the separator does notdepend on the mixture flow to be supplied with an equal distribution ofcomponent parts at any given point in time. In fact, the separator 100is designed handle cyclic flow characteristics in a mixture flow andstill achieve good segregation of component parts of the flow from oneanother such that the component parts may be processed accordingly in anoil production and/or transmission system.

The separator 100 includes upper-tier elongate conduit 102, lower-tierelongate conduit 104, and plurality of connectors 106 extending betweenupper and lower-tier conduits 102, 104. As will be more fully explainedherein, the number of connectors 106 may be chosen based on variousfactors, but as a general rule, a larger number of connectors 106provides more complete segregation of the component parts of a mixtureflow. In the embodiment shown in FIG. 1, both the upper-tier elongateconduit 102 and the lower-tier elongate conduit 104 have an inlet 108,110, respectively, for receiving the mixture flow from a productioncarrier pipe or other transmission pipe (not shown). However, theseparator 100 may also have only a single inlet on one of the upper andlower-tier elongate conduits 102, 104. The upper and lower-tier elongateconduits 102, 104 also each have an outlet 112, 114, respectively, forexpelling substantially segregated component part flows of the mixtureflow out of the separator 100 for further processing or storage by theoil production and/or transmission system. For example, each componentpart flow leaving the outlet 112, 114 may enter a downstreamtransmission or carrier pipeline to deliver the respective componentpart flows to areas where they can be processed (e.g., deliver liquidpetroleum from the separator 100 on a sea floor to an oversea platformfor processing). The outlets 112, 114 preferably connect with anothercomponent of a closed system (whether a transmission or carrierpipeline, or otherwise) to maintain pressurization of the mixture flowthrough the separator 100 and thereby achieve efficient component partsegregation.

The inlet 108 and the outlet 112 of the upper-tier elongate conduit 102are located at an upstream end 116 and a downstream end 118,respectively, of the conduit 102. Likewise, inlet 110 and the outlet 114of the lower-tier elongate conduit 104 are located at an upstream end120 and a downstream end 122, respectively, of the conduit 104. FIG. 1also shows one embodiment of the separator 100 where the upper andlower-tier elongate conduits 102, 104 are arranged in a verticalalignment with respect to one other, such that the connectors extendaway from a horizontal reference plane (i.e., a sea floor or othersurface) underlying the separator 100. The upper and lower-tier elongateconduits 102, 104 may also be parallel with each another, and theconnectors 106 may be equally spaced from one another and orthogonallyaligned with respect to the conduits 102, 104. It should be understood,however, that different configurations and spatial relationships for theupper and lower-tier elongate conduits 102, 104 and the plurality ofconnectors may be envisioned by those of skill in the art depending onthe desired mixture flow separation results. The separator 100 may alsobe fabricated from a variety of materials, but preferably includesmetals that have substantial strength to withstand the hoop stress andother stresses that will be placed on the separator when placed intoservice. Additionally, the connectors 106 are preferably welded to theupper and lower-tier elongate conduits 102, 104 to form the separator100 as a rigid, monolithic unit.

The flow pattern for one exemplary mixture flow including a gascomponent and a liquid component traveling through the separator 100 isshown in FIG. 2. The connectors 106 facilitate the movement of a lowerdensity component part of the mixture flow (e.g., the gas component,whose flow pattern within the separator 100 is indicated by black arrowsG) and the higher density component part of the mixture flow (e.g., theliquid component, whose flow pattern within the separator 100 isindicated by the white arrows L) between the upper and lower-tierelongate conduits 102, 104 acting under the principles of buoyancy. Theupper-tier elongate conduit 102 has a plurality of spaced apart openings124 on one longitudinal side 126 thereof, and the lower-tier elongateconduit 104 has a plurality of spaced apart openings 128 on onelongitudinal side 130 thereof. Each connector 106 interconnects theupper and lower-tier elongate conduits 102, 104 together by extendingfrom one opening 124 of the upper-tier elongate conduit 102 to acorresponding opening 128 of the lower-tier elongate conduit 104. Aproduction carrier pipe may deliver mixture flow directly to either ofthe inlets 108, 110 of the upper and lower-tier conduits 102, 104,respectively, and a secondary transmission pipe may split off from theproduction carrier pipe upstream of the separator 100 to deliver aportion of the original mixture flow being transmitted by the productioncarrier pipe to another one of the inlets 108, 110 of the upper andlower-tier conduits 102, 104, respectively. Thus, the mixture flow intothe inlets 108, 110 of the upper and lower-tier conduits 102, 104,respectively, may arrive at a predetermined velocity. It should beunderstood, however, that other conduits besides production carrierpipes may be implemented to supply mixture flow to the separator 100.

When the mixture flow takes on the characteristics of slug flow, thedifferent mixture flows received by each inlet 108, 110 at anyparticular point in time may not possess the same physical properties orcomponent distribution as the mixture flow received at the other inlet.However, this discrepancy between the mixture flows can be managed bythe separator 100 in a closed transmission system supplying mixture flowunder pressure, principally because the separator 100 utilizes buoyancyprinciples to progressively separate component parts of the mixture flowmoving from the inlets 108, 100 to the outlets 112, 114 of theseparator. As can be seen in further detail in FIG. 2, the percentage byweight of the liquid component flow L in the mixture flow increases inthe lower-tier elongate conduit 104 moving downstream as more liquidcomponent in the upper-tier elongate conduit 102 falls down through theconnectors 106 under the force of gravity. Likewise, the percentage byweight of the gas component flow G increases in the upper-tier elongateconduit 102 as more gas component in the lower-tier elongate conduit 104rises up through the connectors 106 by buoyancy, being displaced out ofthe lower-tier elongate conduit 104 by the increasing amount of liquidcomponent therein. Thus, under this separation regime, even if slug flowis encountered, so long as the interior volume of the separator 100 issufficiently large to handle a given hydrodynamic slug volume, buoyancyprinciples will ensure that gas and/or liquid slugs will substantiallyflow to the appropriate one of the upper or lower-tier elongate conduit102 or 104 by the time the mixture flow reaches the respective outlet112 or 114.

To optimize the efficiency of flow characteristics of the mixture flowcomponents (e.g., the liquid component and gas component), the upper andlower-tier elongate conduits 102, 104 and the connectors 106 arepreferably cylindrical members, and thus have a circular or ellipticalcross-section longitudinally. However, other cross-sectional shapes maybe utilized as well. Additionally, in selecting a certain number ofconnectors 106 for the separator 100 necessary to achieve a desiredlevel of mixture flow separation under a variety of flow regimes, themaximum hydrodynamic slug volume expected in mixture flows through theseparator is preferably taken into consideration, as previouslymentioned. Accordingly, the number of connectors 106 is an amountnecessary to make the total interior volume of the separator greaterthan the maximum hydrodynamic slug volume expected. The calculation forthe total interior volume involves summing up of the interior volumes ofthe upper-tier elongate conduit 102, the lower-tier elongate conduit104, and the connectors 106 for the given numbers of connectors. Theinterior volume of the upper and lower-tier elongate conduits 102, 104,and the connectors 106, may be determined from the chosen length andinside diameters of each. When separating mixture flow components underconditions where one of the component parts is a liquid and another ofthe component parts is a gas or a liquid of a differentdensity—especially when one of the liquids is petroleum—efficientmixture flow separation is facilitated if one or more of the connectors106 has a length that is at least about five times the inside diameterthereof or greater, or if this length to diameter ratio is not possible,then a length of at least about five meters. This connector 106configuration allows a liquid component entrained in the gas componentflow G moving up one of the connectors 106 to settle out and drop backdown to the lower-tier elongate conduit 104.

The separator 100 can also be optimally designed for certain flowregimes of the mixture flow. For instance, if a mixture flow expected tobe encountered involves high flow velocities and a low percentage byvolume of any liquid component present in the flow (i.e., a highpercentage by volume of gas), a majority of the liquid component willflow with the accompanying gas component as entrained drops, with aportion of the liquid component flowing along an inside wall of theupper and lower-tier elongate conduits 102, 104. In this flow regime,only a small percentage of the liquid component will enter a givenconnector 106, and thus, a large number of connectors 106 will typicallybe necessary for the separator 100 to achieve strong segregation of thecomponent part flows.

More freedom is provided the separator 100 designer when a flow regimeinvolving intermediate mixture flow velocities and a moderate to highpercentage by volume of any liquid component present in the flow. Underthese conditions, slug flow often occurs. However, the separator 100 canusually achieve strong segregation of the component part flows even withonly a moderate number of connectors 106. At intermediate mixture flowvelocities and low percentage by volume of any liquid component presentin the flow, and at low mixture flow velocities and nearly all liquidpercentages, the separator 100 can often achieve strong segregation ofthe component part flows with only a small number of connectors (e.g., 3or more).

The separator 100 may also be oriented as downward sloping relative to ahorizontal reference plane (e.g., the sea floor or other surface), asshown in FIG. 3. In this arrangement, the angle α measures the degree ofdownward slope of the upper and/or lower-tier elongate conduits 102,104. Separation of the mixture flow into component parts takes placewith generally the same principles as a separator with no downwardslope, with the difference lying in the stratification of the mixtureflow, especially when in the form of a slug flow. The downward slopeincreases the velocity of any liquid component of the mixture flow dueto gravity, which increases the degree of stratification with othercomponent parts of differing densities within the mixture flow movingtowards the downstream ends 120, 122 of the upper and lower-tierelongate conduits 102, 104, respectively. This stratificationfacilitates increased separation of the component parts of the mixtureflow from one another. It has been found that at an angle α of about 30to about 60, for example about 45 degrees for a downward slope of theseparator 100 may be used for development of stratified flow for a rangeof flow regimes, though other angles will also facilitate goodstratified flow. However, it should be understood that the separator 100may be oriented in an upward sloping arrangement if necessary forcertain applications (e.g., integration of the separator into atransmission line moving up a sloped surface), so long as the upper andlower-tier elongate conduits 102, 104 are not longitudinally aligned ina vertical plane orthogonal to the horizontal reference plane.

If excessive slug flow is not encountered by the transmission or carrierpipeline delivering the mixture flow to the separator 100, then acentrifugal separation device (not shown) may be coupled to the inlets108, 110 of the upper and lower-tier elongate conduits 102, 104,respectively, the flow pattern within the centrifugal separation devicebeing represented by the dashed lines in FIG. 3. Accordingly, a mixtureflow (e.g., a gas and liquid flow) enters the centrifugal separationdevice, and a portion of the gas component flow is extracted anddirected to the inlet 108 of the upper-tier elongate conduit 102. Theremaining portion of the mixture flow now having a higher concentrationof liquid component moves through the centrifugal separation device tothe inlet 110 of the lower-tier elongate conduit 104. Thus, this firststage of mixture flow separation conducted by the centrifugal separationdevice enables the separator 100 to achieve strong segregation of thecomponent part flows with fewer numbers of connectors 106.

Another embodiment of the separator 100 is shown in FIG. 4, where theupper-tier elongate conduit 102 has no inlet. The only inlet for theseparator 100 is the inlet 110 of the lower-tier elongate conduit 104.Thus, the upper-tier elongate conduit 102 should have virtually noamount of the higher density component flow therein. This arrangement iseffective when the lower density component flow (e.g., gas) issufficiently low in density compared to the higher density componentflow of the mixture flow, such that the lower density component willeasily be displaced into the upper-tier elongate conduit 102.Progressive separation of the component flows is still achieved movingdownstream when a sufficient number of connectors 106 are used. As canbe seen, the predominant flow pattern within the connectors 106 is alower density component flow moving upward to the upper-tier elongateconduit 104.

Further refinement of techniques for mixture flow separation is possiblewith the embodiment of the separator 100 shown in FIG. 5. The separator100 of FIG. 5 includes the upper and lower-tier elongate conduits 102,104 and connectors 106, but further comprises another plurality ofconnectors 132 and a third tier elongate conduit 134. The third tierelongate conduit 134 is generally positioned opposite the upper-tierelongate conduit 102 relative to the lower-tier elongate conduit 104.For example, the third tier elongate conduit 134 may be positioneddirectly above the upper-tier elongate conduit 102. Another plurality ofspaced apart openings 136 are provided on the upper-tier elongateconduit 102 on a longitudinal side 138 thereof opposite of thelongitudinal side 126 wherein the plurality of spaced apart openings 124are located. The third tier elongate conduit 134 also has a plurality ofspaced apart openings 140 on a longitudinal side 142 thereof. Eachconnector 132 interconnects the upper and third tier elongate conduits102, 134 together by extending from one opening 136 of the upper-tierelongate conduit 102 to a corresponding opening 140 of the third tierelongate conduit 134, enabling communication of the component part flowsof the mixture flow to travel therethrough. The third tier elongateconduit 134 may have an inlet 144 and an outlet 146 in a similar fashionto the inlet 108 and outlet 112 of the upper-tier elongate conduit 102,and a production carrier pipe or other secondary pipe may deliver amixture flow to the inlet 144. By having three tiers of elongateconduits, the separator 100 of FIG. 5 provides an increased distance forlower density flow components to move via displacement, and higherdensity flow components to move via gravity, through the connectors 106,132 to a respective tier of the elongate conduits 102, 104, 134.Furthermore, the separator 100 of FIG. 5 is well suited for separating amixture flow having three component parts of differing densities (e.g.,gas, water, and petroleum) into three component part flows through therespective outlets, with the highest density component flow leaving theoutlet 104 of the lower-tier elongate conduit 104, the lowest densitycomponent flow leaving the outlet 146 of the third tier elongate conduit134, and the middle density component flow leaving the outlet 112 of theupper-tier elongate conduit 102.

FIG. 6 shows a separation system 200 incorporating the principles ofmixture flow separation utilized by the separator 100, but withincreased throughput. One or more supply lines 202 (e.g., transmissionor carrier pipeline) deliver the mixture flow to one or both of an arrayof upper-tier elongate conduits 204 and an array of lower-tier elongateconduits 206. For example, in the embodiment shown in FIG. 6, the arraysof upper and lower-tier elongate conduits 204, 206 have inlets 208, 210,respectively.

An upper inlet header 212 may be provided with the array of upper-tierelongate conduits 204, and a lower inlet header 214 may be provided withthe array of lower-tier elongate conduits 206. The upper and lowerheaders 212, 214 divide the incoming mixture flows received through theinlets 208, 210, respectively, into individual upper-tier elongateconduits 102 and lower-tier elongate conduits 104, respectively.

The upper-tier elongate conduits 102 of the array 204 are laterallyspaced apart from one another and are preferably generally aligned inthe same lateral plane. Likewise, the lower-tier elongate conduits 104of the array 206 are laterally spaced apart from one another and arepreferably generally aligned in the same lateral plane. A plurality ofthe connectors 106 interconnect the array of upper-tier elongateconduits 204 with the array of lower-tier elongate conduits 206 to allowcommunication of mixture flow component parts therebetween. The array ofupper-tier elongate conduits 204 may overlie the array of lower-tierelongate conduits 206 such that each individual upper-tier elongateconduit 102 may interconnect with a corresponding one of the lower-tierelongate conduits 104 through a given set of the connectors 106.

An upper outlet header 216 may be provided with the array of upper-tierelongate conduits 204, and a lower outlet header 218 may be providedwith the array of lower-tier elongate conduits 206. The upper and loweroutlet headers 216, 218 may recombine the downstream flows received fromthe arrays of upper and lower-tier elongate conduits 204, 206,respectively—which are now substantially separated into respectivecomponent part flows—and expel the flows out of outlets 220, 222 of thearrays of upper and lower-tier elongate conduits 204, 206, respectively,for further processing of the component part flows as explained hereinwith respect to the separator 100 of FIGS. 1 and 2. The downstreamcomponent part flows may be, for example, expelled out of the outlets220, 222 into takeoff lines (not shown).

One advantage to using the separation system 200 of FIG. 6 over theseparator 100 of FIG. 2 is space requirements in some applications. Whena large flow rate of a mixture is encountered, the utilization of only asingle upper-tier elongate conduit 102 and a single lower-tier elongateconduit 104 may in certain circumstances require exceedingly longconnectors 106 to allow for efficient movement of component parts of themixture flow. However, there may not be enough vertical room in certainlocations where separation must take place for a very tall device. Theuse of arrays of upper and lower-tier elongate conduits 204, 206provides the ability to use a larger number of conduits of a shorterlength to achieve efficient mixture flow separation.

In some embodiments, upper-tier elongate conduit 102, lower-tierelongate conduit 104, and/or plurality of connectors 106 have across-sectional area at least about 125% of the cross-sectional area ofinlets 108, 110 and/or inlet production carrier pipe or othertransmission pipe (not shown), for example at least about 150%, or atleast about 200%.

In some embodiments, plurality of connectors 106 is between about 2 andabout 100 connectors, for example between about 5 and about 50connectors, or between about 10 and about 20 connectors.

EXAMPLE

A separator 100 was constructed out of 4-inch transparent PVC pipe,having upper and lower-tier elongate conduits 102, 104 formed with alength of about 30 feet, and 12 connectors 106 each being about 10.5inches long and spaced about 29 inches apart center-to-center.Inclination angles (i.e., the negative value of downward sloping angleα) were chosen over a broad range of values. In an upward slopingarrangement for the separator 100, the internal volume of the connectors106 is preferably around one-third the total internal volume of theseparator. Therefore, the upper and lower-tier elongate conduits 102,104 are each about 66.7 diameters long, and the connectors are eachabout 5.56 diameters long. The results of the experiment are shown inthe following table:

Liquid Inlet Outlet Rate in % Inclination Gas Liquid Inlet Temper-Outlet Temper- Gas Liquid Test angle, Rate, Rate, Pressure, ature,Pressure, ature, Outlet, in Gas Number degree scf/min gpm psig F. psigF. gpm Outlet 1 19.5 99.9 180.6 33.9 89.7 0 89.6 1.98 1.1 2 41 101 181.134.3 76.8 0 76.8 0.83 0.5 3 41 107.7 69.3 15 79 0 78.7 0 0 4 20.5 124.35119.56 35.4 88.8 0 88.3 0.528 0.4 5 30.5 200 200 22.4 85.7 0 94.7 0 0 650.75 243.2 121.1 35.9 91.5 0 91 1.98 1.6 7 9.5 245 119.21 37.3 89.7 089.3 1.056 0.9 8 3.6 52.8 129.5 17 79.9 0 76 4.529 3.5 9 3.6 108.9128.35 22.5 71.5 0 67 2.438 1.9 10 3.6 99.6 179.35 32 91.2 0 85 6.34 3.511 14 99.2 182.1 33 87 0 87 3.96 2.2 12 19.5 99.9 180.2 34 86.8 0 86.81.98 1.1

As can be seen from the chart, the separator 100 provides goodseparation of the liquid component part from the gas component part flowat a variety of flow rates, even when the separator is placed at a rangeof upwardly sloping inclination angles.

Therefore, the slug flow separator of the present invention provides asolution for managing slug flows and separating component parts of theslug flow in an apparatus that may easily be integrated with existingproduction carrier pipes and other transmission pipes and deployed to avariety of locations. The slug flow separator also requires little to nomaintenance due to the simple design and construction, and may beconfigured with a necessary number of connectors between the tiers(e.g., upper and lower-tier elongate conduits) to achieve progressiveand efficient separation for a variety of anticipated mixture flowstherethrough. Furthermore, since certain changes may be made in theabove invention without departing from the scope hereof, it is intendedthat all matter contained in the above description or shown in theaccompanying drawing be interpreted as illustrative and not in alimiting sense. It is also to be understood that the following claimsare to cover certain generic and specific features described herein.

1. A subsea separation system, comprising: a producing well on a seafloor comprising a production pipe outlet, the production pipe outletcomprising a mixture of oil, water and various gases; a separator on thesea floor connected to the producing well, the separator comprising: anupper-tier elongate conduit having a plurality of openings spaced apartalong the length thereof and an outlet for the various gases; alower-tier elongate conduit having a plurality of openings spaced apartalong the length thereof and an outlet for the oil and water; aplurality of connectors, each connector interconnecting a correspondingone of the plurality of openings of the upper-tier elongate conduit witha corresponding one of the plurality of openings of the lower-tierelongate conduit to enable communication of the various gases and theoil and water therebetween; and wherein at least one of the upper-tierand lower-tier elongate conduits includes an inlet connected to theproduction pipe outlet; a gas export pipeline connected to the outletfor the various gases at a first end and a second end connected to aproduction facility located on a surface of a body of water or on land;and a liquid export pipeline connected to the outlet for the oil andwater at a first end and a second end connected to the productionfacility.
 2. The system of claim 1, wherein the lower-tier elongateconduit extends generally in the same direction as the upper-tierelongate conduit.
 3. The system of claim 1, wherein both of theupper-tier and lower-tier elongate conduits include an inlet connectedto the production pipe outlet.
 4. The system of claim 1, wherein theplurality of connectors are equally spaced along the length of theupper-tier and lower-tier elongate conduits.
 5. The system of claim 1,wherein the plurality of connectors are aligned orthogonally withrespect to both of the upper-tier and lower-tier elongate conduits. 6.The system of claim 1, wherein the upper-tier elongate conduit comprisesa production carrier pipe and the lower-tier elongate conduit comprisesa secondary pipe.